EXPERIMENTAL STUDY ON SWELLING CHARACTERISTICS OF SAND-BENTONITE MIXTURE FOR NUCLEAR WASTE DISPOSAL
EXPERIMENTAL STUDY ON SWELLING CHARACTERISTICS OF SAND-BENTONITE MIXTURE FOR NUCLEAR WASTE DISPOSAL
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DOI：
10.3208/sandf.39.2_83
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发表时间：
1999-04
影响因子：
3.7
通讯作者：
H. Komine;N. Ogata
中科院分区：
文献类型：
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作者：
H. Komine;N. Ogata
摘要砂和膨润土的混合物被认为是核电站放射性废物处置设施人工屏障的有效组成部分。因此，为了设计和建造这些设施，我们必须评估砂-膨润土混合物的膨胀特性。为此，对砂-膨润土混合物的膨胀压力和膨胀变形进行了各种室内试验。为了探讨这些混合物的溶胀特性的过程中，本研究还观察了膨润土在混合物中的溶胀行为，使用扫描电子显微镜，可以控制样品周围的温度和蒸汽压。通过本研究得出以下结论。(i)砂-膨润土混合物的膨胀特性取决于混合物的干密度和膨润土含量。(ii)通过扫描电镜观察发现，膨润土吸水后，混合料中的空隙被体积增大所填充。此外，基于膨润土的膨胀行为，研究了砂-膨润土混合物的膨胀过程。（iii）提出了用“膨润土的膨胀体积应变”参数来评价砂-膨润土混合物的膨胀特性。该评价方法可以得到不同干密度和膨润土含量下砂-膨润土混合物的最大膨胀压力和最大膨胀应变。因此，在设计和建造核废物处置设施时，这种简化的评价方法是可行的。
ABSTRACT A mixture of sand and bentonite is seen as an effective component of artificial barriers for disposal facilities of radioactive wastes from nuclear power stations. Therefore, to design and construct these facilities, we must evaluate the swelling characteristics of sand-bentonite mixtures. For this purpose, various laboratory tests on the swelling pressure and swelling deformation of sand-bentonite mixtures were performed. To discuss the process of the swelling characteristics of these mixtures, this study also observed the swelling behavior of bentonite in the mixtures using a scanning electron microscope which can control the temperature and vapor pressure around samples. The following conclusions were obtained through this study. (i) The swelling characteristics of sand-bentonite mixtures is dependent on the dry density and bentonite content of mixtures. (ii) From observation with the scanning electron microscope, we found that the voids of mixtures are filled up by the volume increase when bentonite absorbs water. Furthermore, the swelling process of sand-bentonite mixtures was considered on the basis of the swelling behavior of montmorillonite, a swelling clay mineral. (iii) This study proposes the simplified evaluation of the swelling characteristics of sand-bentonite mixtures using the parameter “Swelling volumetric strain of montmorillonite”. This evaluation can obtain the maximum swelling pressure and the maximum swelling strain of sand-bentonite mixtures at various dry densities and bentonite contents. Therefore, this simplified evaluation is available when the disposal facilities of nuclear wastes will be designed and constructed.